88 
Duns. Cordaites or other reed-like plants are the only type of 
fossils found in situ immediately over the coal in the Bristol. 
coalfield, the larger forms of vegetation in the roof have evi- 
dently been drifted into their position. 
The finding of the coalstones, their origin being as stated, 
also goes far to support this view. 
Again, coal seams have an even thickness often for miles, 
and it is not difficult to imagine a land surface being sub- 
merged on which were forests of large trees, that would subse- 
quently form a seam of coal of uniform thickness. 
These trees could not grow together in such close proximity 
as to form a compact mass, nor could they fall into such, yet it 
is difficult to imagine a seam of coal being formed by any 
other than a compact mass during submergence. 
At Speedwell Colliery, near Bristol, a thin seam of coal was 
cut which contained Sigillaria, but it was worthless for fuel, 
as the following analysis will show: 
Ash 5 ES Us ... 29°40 
Fixed carbon oe ah ... 65°48 
Moisture ... Nas e Axe 1-23 
Volatile matter... ie ... 18°89 
100-00 
The great peat and lignite beds of more modern formations 
are not composed of large trees but of mosses and reeds. 
Professor O. Herr in his notes on fossil plants discovered in 
Grinnell Land, thus refers to the lignite bed. 
“The thick Lignite bed of Grinnell Land would indicate a 
large peat moss in which most probably a small lake existed. 
On the shallow bottom of this lake the great rhizomes of the 
water-lilies might spread and from them the leaves would rise 
to the surface of the water. On the muddy shore stood the 
large reeds and the Sedges (carices), the Birches, and the 
Poplars, the Taxodia with their graceful foliage, and the 
rigid-leaved Torelliz. 
The dryer spots and neighbouring chains of hills were probably 
occupied by the Polar and Feilden pines, by the Firs, the Hem- 
locks, and the Hayes-spruce. 
